1. Field of the Invention
The present invention relates to an ink-jet recording head, a method for manufacturing the ink-jet recording head, and a semiconductor device.
2. Description of the Related Art
In the field of semiconductor devices, the following technique has been recently proposed to meet the need for downsizing portable electronic devices: a technique for three-dimensionally arranging devices to increase the packing density of the devices. The technique is as follows: semiconductor devices that have been two-dimensionally arranged are three-dimensionally arranged and signals are transmitted between the semiconductor devices through electrodes (through-hole electrodes) extending through each substrate having the semiconductor devices. The technique is more effective in achieving higher device-packing density as compared to conventional techniques for transmitting signals between two-dimensionally arranged semiconductor devices through wires arranged on printed circuit boards and is effective in downsizing apparatuses.
In the field of ink-jet recording heads (hereinafter referred to as recording heads in some cases), structures having supply ports extending through substrates have been proposed for various purposes. Japanese Patent Laid-Open No. 9-11478 discloses a recording head in which a protective layer is formed on the wall of a supply port such that a material (for example, silicon) for forming a substrate is prevented from being dissolved in ink.
A signal can be transmitted between the recording head and a recording unit body located on the side of the rear surface (a surface opposed to another surface having nozzles) of the recording head through a through-hole electrode. This configuration requires no wires for transmitting a signal. This leads to a reduction in the distance between the recording head and a recording medium, resulting in an increase in ink-landing accuracy. Therefore, high-quality images can be output.
In order to form through-hole electrodes in a semiconductor device, an insulating layer for insulating a conductive layer from a substrate needs to be formed. The insulating layer must be prevented from being peeled off from the conductive layer or the substrate if an external force is applied to the insulating layer in, for example, a step of bonding the semiconductor device to external electrodes. If a material having low affinity to other materials is used to form the insulating layer, the peeling of the insulating layer can particularly occur.
The recording head has the same problem as described above if the supply port is replaced with a through-hole present in the semiconductor device and the protective layer is replaced with the insulating layer. The ink used in the recording head may enter the interface between the substrate and the protective layer, which is disposed on the wall of the supply port. If the ink reaches the substrate and circulates through penetration routes, a large amount of the substrate material is dissolved in the ink. This causes a problem such as the blocking of discharge ports. Recording heads including such through-hole electrodes and supply ports have the same problem as described above.